1. Field of the Invention
This invention relates generally to fluid delivery devices, and relates more particularly to a fluid medication delivery device for application of fluid medications to a surface area of the skin of a patient.
2. Description of the Related Art
Transdermal patches are a known mechanism for delivering pharmaceutical substances, such as fluid medications, to a patient by passing such fluids through the patient's skin. Transdermal patches are utilized for treatments such as hormone replacement therapy and smoking cessation, for example. One type of transdermal patch contains an unreplenishable supply of a pharmaceutical substance. The patch has a skin-contacting adhesive layer to facilitate in adhering the patch to the skin. Typically, such a transdermal patch is adhered to a suitable area of the skin for a period of time, during which the substance is delivered to the patient.
Once the pharmaceutical substance within the patch is substantially exhausted, the patch is removed from the skin. If more of the substance must be delivered to the patient, a subsequent patch must be applied and, in order to avoid irritation to the skin of the patient, often to a different location on the patient's skin. One drawback to using this type of transdermal patch is that, for certain patients, a new area of the skin must be sought for the application of each subsequent patch. Thus, if such patches must be used for an extended period of time, it may become increasingly difficult to find an available area of the skin suitable for application of the patch. Another drawback is that such a transdermal patch contains a fixed initial quantity (i.e., volume) of a pharmaceutical substance, and thus individual patches are incapable of delivering large volumes of such substances, such as medicinal fluids.
Another type of patch includes an injection port that permits refilling of the patch with a pharmaceutical substance using a hypodermic needle. Although such an arrangement permits the patch to be refilled, the refilling process should be carried out by a health care worker in order to prevent injury to the patient or damage to the patch due to the use of the hypodermic needle. As a result, frequent visits to a health care facility, or frequent home visits of a health care worker, are necessary to refill the patch. Accordingly, the convenience of such an arrangement is less than ideal. Furthermore, the use of a hypodermic needle presents a significant risk to the health care worker, as accidental pricking or stabbing of the health care worker often accompanies to use of a hypodermic needle, or other sharp medical instrument.
Other patch-type fluid delivery arrangements allow for connection to an external fluid supply, but utilize complicated mechanisms for urging delivery of the pharmaceutical substance and/or do not provide for uniform delivery over the area of the patch. Accordingly, a need exists for an improved transdermal patch that overcomes the limitations of the prior art.